The usual method for locating breaks in water mains below a hard surface, concrete for example, or a softer surface such as soil is to use manually operated pneumatic jack hammers, steamers and even brute force, i.e., pick axes and the like.
Contemporary methods now utilize drill towers mounted on many types of prime movers such as trucks, with the drill towers comprising twin masts, one mast mounting on air-powered rotary percussion drill and the other mast mounting a hydraulic powered auger. The towers are movable as a unit fore and aft a short distance, sixteen inches for example, and laterally the distance between their center lines. This method requires a continuous shifting of the entire twin-mast structure on its mounting unit for drilling a single hole.